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can be specified
Currently MySQL allows one to specify what indexes to ignore during
join optimization. The scope of the current USE/FORCE/IGNORE INDEX
statement is only the FROM clause, while all other clauses are not
affected.
However, in certain cases, the optimizer
may incorrectly choose an index for sorting and/or grouping, and
produce an inefficient query plan.
This task provides the means to specify what indexes are
ignored/used for what operation in a more fine-grained manner, thus
making it possible to manually force a better plan. We do this
by extending the current IGNORE/USE/FORCE INDEX syntax to:
IGNORE/USE/FORCE INDEX [FOR {JOIN | ORDER | GROUP BY}]
so that:
- if no FOR is specified, the index hint will apply everywhere.
- if MySQL is started with the compatibility option --old_mode then
an index hint without a FOR clause works as in 5.0 (i.e, the
index will only be ignored for JOINs, but can still be used to
compute ORDER BY).
See the WL#3527 for further details.
101 lines
4.1 KiB
Text
101 lines
4.1 KiB
Text
#
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# Test problem with characters < ' ' at end of strings (Bug #3152)
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#
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-- source include/have_innodb.inc
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--disable_warnings
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drop table if exists t1;
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--enable_warnings
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-- source include/endspace.inc
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#
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# Test MyISAM tables.
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#
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create table t1 (text1 varchar(32) not NULL, KEY key1 (text1));
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insert into t1 values ('teststring'), ('nothing'), ('teststring\t');
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check table t1;
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select * from t1 ignore key (key1) where text1='teststring' or
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text1 like 'teststring_%' ORDER BY text1;
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select * from t1 where text1='teststring' or text1 like 'teststring_%';
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select * from t1 where text1='teststring' or text1 > 'teststring\t';
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select * from t1 order by text1;
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explain select * from t1 order by text1;
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alter table t1 modify text1 char(32) binary not null;
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check table t1;
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select * from t1 ignore key (key1) where text1='teststring' or
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text1 like 'teststring_%' ORDER BY text1;
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select concat('|', text1, '|') from t1 where text1='teststring' or text1 like 'teststring_%';
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select concat('|', text1, '|') from t1 where text1='teststring' or text1 > 'teststring\t';
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select text1, length(text1) from t1 order by text1;
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select text1, length(text1) from t1 order by binary text1;
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alter table t1 modify text1 blob not null, drop key key1, add key key1 (text1(20));
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insert into t1 values ('teststring ');
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select concat('|', text1, '|') from t1 order by text1;
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select concat('|', text1, '|') from t1 where text1='teststring' or text1 > 'teststring\t';
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select concat('|', text1, '|') from t1 where text1='teststring';
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select concat('|', text1, '|') from t1 where text1='teststring ';
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alter table t1 modify text1 text not null, pack_keys=1;
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select concat('|', text1, '|') from t1 where text1='teststring';
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select concat('|', text1, '|') from t1 where text1='teststring ';
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explain select concat('|', text1, '|') from t1 where text1='teststring ';
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select concat('|', text1, '|') from t1 where text1 like 'teststring_%';
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select concat('|', text1, '|') from t1 where text1='teststring' or text1 like 'teststring_%';
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select concat('|', text1, '|') from t1 where text1='teststring' or text1 > 'teststring\t';
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select concat('|', text1, '|') from t1 order by text1;
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drop table t1;
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create table t1 (text1 varchar(32) not NULL, KEY key1 (text1)) pack_keys=0;
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insert into t1 values ('teststring'), ('nothing'), ('teststring\t');
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select concat('|', text1, '|') from t1 where text1='teststring' or text1 like 'teststring_%';
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select concat('|', text1, '|') from t1 where text1='teststring' or text1 >= 'teststring\t';
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drop table t1;
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# Test HEAP tables (with BTREE keys)
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create table t1 (text1 varchar(32) not NULL, KEY key1 using BTREE (text1)) engine=heap;
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insert into t1 values ('teststring'), ('nothing'), ('teststring\t');
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select * from t1 ignore key (key1) where text1='teststring' or
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text1 like 'teststring_%' ORDER BY text1;
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select * from t1 where text1='teststring' or text1 like 'teststring_%';
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select * from t1 where text1='teststring' or text1 >= 'teststring\t';
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select * from t1 order by text1;
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explain select * from t1 order by text1;
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alter table t1 modify text1 char(32) binary not null;
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select * from t1 order by text1;
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drop table t1;
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#
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# Test InnoDB tables
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#
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create table t1 (text1 varchar(32) not NULL, KEY key1 (text1)) engine=innodb;
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insert into t1 values ('teststring'), ('nothing'), ('teststring\t');
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check table t1;
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select * from t1 where text1='teststring' or text1 like 'teststring_%';
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select * from t1 where text1='teststring' or text1 > 'teststring\t';
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select * from t1 order by text1;
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explain select * from t1 order by text1;
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alter table t1 modify text1 char(32) binary not null;
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select * from t1 order by text1;
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alter table t1 modify text1 blob not null, drop key key1, add key key1 (text1(20));
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insert into t1 values ('teststring ');
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select concat('|', text1, '|') from t1 order by text1;
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alter table t1 modify text1 text not null, pack_keys=1;
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select * from t1 where text1 like 'teststring_%';
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# The following gives wrong result in InnoDB
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select text1, length(text1) from t1 where text1='teststring' or text1 like 'teststring_%';
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select text1, length(text1) from t1 where text1='teststring' or text1 >= 'teststring\t';
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select concat('|', text1, '|') from t1 order by text1;
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drop table t1;
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# End of 4.1 tests
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